WO2018211704A1

WO2018211704A1 - Lighting apparatus, imaging system containing said lighting apparatus, and microscope system and endoscope system containing said imaging system

Info

Publication number: WO2018211704A1
Application number: PCT/JP2017/018894
Authority: WO
Inventors: 山本　英二; 麦穂大道寺; 佐々木　靖夫
Original assignee: オリンパス株式会社
Priority date: 2017-05-19
Filing date: 2017-05-19
Publication date: 2018-11-22
Also published as: US20200081264A1; CN110637250A

Abstract

This lighting apparatus (102) comprises a lighting pulse generator (110) which generates a lighting pulse of coherent light, a speckle modulator (200) which modulates speckle generated by the coherent light, and a synchronization controller (240) which performs control by synchronizing the pulse generation timing of the lighting pulse generator and the driving timing of the speckle modulator.

Description

Illumination device, imaging system including the illumination device, endoscope system and microscope system including the imaging system

The present invention relates to a lighting device using coherent light.

In an imaging system that uses coherent light, such as a laser light source, for illumination, if the observation target has a scattering structure such as slight irregularities, a fine speckle pattern occurs on the imaging surface of the imager, and the acquired image It is known that it appears as noise (this is called speckle noise) and hinders visibility. This phenomenon is not limited to electronic imaging systems, but also occurs on the retina of the living body corresponding to the imaging surface, so the same problem occurs with illumination devices that use coherent light for illumination, such as laser projectors. To do. The cause of this speckle is known to be that light scattered from the unevenness of the observation object interferes and a fine light-dark pattern is formed on the imaging surface or the retina.

A variety of speckle reduction methods are known to reduce this, and typical ones are listed below. In the following description, “coherent light” is often described as “laser light” as a representative example, but in this specification, it can be read as general “coherent light”. The general “coherent light” also includes “partial coherent light”.

(1) [Method of reducing speckle noise by reducing the effective coherence of the light source itself]
(1-a) When an LD (laser diode) is driven by current, high frequency superposition or the like is performed as a drive waveform to promote multimode spectrum and widen the effective spectrum width.
(1-b) The LD is equipped with a self-pulsation function to disturb the phase and wavelength of light.
(1-c) The spectrum of the tunable laser is changed at high speed to widen the effective spectrum width.
(1-d) A combination of a plurality of mutually independent lasers reduces the effective coherence.

(2) [Method for reducing effective speckle noise by temporally changing the light / dark pattern due to speckle and utilizing the temporal superposition effect of the light / dark pattern]
(2-a) The observation target is vibrated to change the speckle pattern.
(2-b) The speckle pattern is changed by causing a change in the optical phase in the optical path from the light source to the observation target.

As an example of (2-b), in a configuration in which laser light is guided by an optical fiber and irradiated, the shape and stress of the optical fiber are changed, and the temporal light guide mode is changed to change the laser light to be irradiated. A method for causing a phase change and changing a speckle pattern has been proposed.

For example, Japanese Patent Application Laid-Open No. 2003-156698 discloses a laser light source device having such a configuration. In this laser light source device, laser light emitted from the laser light source enters the incident end of the optical fiber, and is emitted from the emission end as laser illumination light. An excitation device that applies vibration to the optical fiber is provided at an intermediate portion of the optical fiber. When the optical fiber is vibrated by this vibration device, a light phase change occurs due to laser beam mode conversion or the like inside the optical fiber. Due to the characteristic change of the laser beam (here, the optical phase change), the stripe pattern due to speckles generated when the observation target is irradiated from the optical fiber moves or changes. Because this speckle stripe pattern moves or changes at a speed that human eyes cannot perceive, humans feel that the speckle stripe pattern is superimposed and averaged, Speckle noise will be reduced.

The above-mentioned method (1-a) is limited to the LD as a laser that can be used. The spread of the spectrum differs depending on the individual difference of the LD, and a stable and sufficient effect for reducing speckles cannot always be obtained. Many. The methods (1-b) and (1-c) require a laser integrated with a special function, and the method (1-d) requires a large number of lasers and has a sufficient reduction effect. In order to realize an imaging system that exhibits it, it must be expensive.

On the other hand, since the method (2-a) is limited to a case where the observation target may be finely oscillated like a projector screen, it is difficult to apply to the observation target such as a microscope or an endoscope. The method (2-b) is a method that does not limit the observation target because it is not necessary to vibrate the observation target. However, since it is necessary to mechanically change the shape and stress of the optical fiber, There are significant restrictions on the modulation speed. Therefore, with this technique, for example, in an electronic imaging system, it is predicted that the speckle pattern overlapping effect cannot be sufficiently exhibited when the imaging frame rate is fast or when the imaging time is short.

An object of the present invention is to provide an illumination device that can stably and effectively reduce speckle noise.

An illumination device according to the present invention includes an illumination pulse generator that generates an illumination pulse of coherent light, a speckle modulator that modulates speckle generated by the coherent light, a pulse generation timing of the illumination pulse generator, and the speckle. It has a synchronous controller that controls the drive timing of the modulator in synchronization.

FIG. 1A shows a speckle modulator composed of a vibration device that vibrates an optical fiber. FIG. 1B shows that the phase and mode of the laser light in the optical fiber are changed temporally and the speckle pattern is changed temporally due to the vibration of the optical fiber. FIG. 1C shows the results of experiments actually conducted by the present inventors, and shows the results of measuring changes in effective speckle contrast with respect to the vibration amplitude X _{mod, 0} of the optical fiber. FIG. 2A shows a spectrum of laser light whose wavelength is temporally changed with a fluctuation width λ _mod . FIG. 2B shows a one-dimensional light intensity distribution of a speckle pattern corresponding to the wavelength fluctuation width λ _mod of the laser light shown in FIG. 2A. FIG. 2C shows the change in effective speckle contrast with respect to the change width Δλ _{mod, 0} of the fluctuation width of the wavelength of the laser beam. FIG. 3A1 shows the speckle modulator drive waveform, the illumination waveform of the illumination pulse generator that is optimally synchronized with the drive waveform, the effective modulation amplitude factor M _eff and the speckle reduction effect as an index of the speckle reduction effect. In particular, the pulse width of the irradiation waveform is shorter than a half of the modulation period of the speckle modulator, and M ₀ <1. FIG. 3A2 shows the speckle modulator drive waveform, the illumination waveform of the illumination pulse generator that is optimally synchronized with the drive waveform, the effective modulation amplitude factor M _eff and the speckle reduction effect that are indicators of the speckle reduction effect. In particular, the pulse width of the irradiation waveform is equal to a half of the modulation period of the speckle modulator, and M ₀ <1. FIG. 3B1 shows the speckle modulator driving waveform, the illumination waveform of the illumination pulse generator that is optimally synchronized with the driving waveform, the effective modulation amplitude factor M _eff and the speckle reducing effect as an index of the speckle reducing effect. In particular, the pulse width of the irradiation waveform is shorter than the half of the modulation period of the speckle modulator, and M ₀ = 1. FIG. 3B2 shows the driving waveform of the speckle modulator, the irradiation waveform of the illumination pulse generator that is optimally synchronized with the driving waveform, the effective modulation amplitude factor M _eff and the speckle reduction effect that are indicators of the speckle reduction effect. In particular, it shows a case where the pulse width of the irradiation waveform is equal to a half of the modulation period of the speckle modulator and M ₀ = 1. FIG. 3C1 shows the speckle modulator drive waveform, the illumination waveform of the illumination pulse generator that is optimally synchronized with the drive waveform, the effective modulation amplitude factor M _eff and the speckle reduction effect as an index of the speckle reduction effect. In particular, the pulse width of the irradiation waveform is shorter than the half of the modulation period of the speckle modulator, and M ₀ = 2> 1. FIG. 3C2 shows the driving waveform of the speckle modulator, the irradiation waveform of the illumination pulse generator that is optimally synchronized with the driving waveform, the effective modulation amplitude factor M _eff and the speckle reduction effect as an index of the speckle reduction effect. In particular, it shows a case where the pulse width of the irradiation waveform is equal to a half of the modulation period of the speckle modulator and M ₀ = 2> 1. FIG. 4A1 shows the speckle modulator driving waveform, the illumination pulse generator irradiation waveform, the effective modulation amplitude factor M _eff as an index of the speckle reduction effect, and the speckle reduction effect with respect to the elapsed time. The modulation amplitude factor M ₀ = 1 and t _mod / 2M ₀ > t _{pw, ill} are shown. FIG. 4A2 shows the speckle modulator driving waveform, the illumination pulse generator irradiation waveform, the effective modulation amplitude factor M _eff as an index of the speckle reduction effect, and the speckle reduction effect with respect to the elapsed time. The modulation amplitude factor M ₀ = 2> 1 and t _mod / 2M ₀ > t _{pw, ill} are shown. FIG. 4B1 shows the speckle modulator driving waveform, the illumination pulse generator irradiation waveform, the effective modulation amplitude factor M _eff as an index of the speckle reduction effect, and the speckle reduction effect with respect to the elapsed time. The modulation amplitude factor M ₀ = 1 and t _mod / 2M ₀ = t _{pw, ill} are shown. FIG. 4B2 shows the speckle modulator driving waveform, the illumination pulse generator irradiation waveform, the effective modulation amplitude factor M _eff as an index of the speckle reduction effect, and the speckle reduction effect with respect to the elapsed time. The modulation amplitude factor M ₀ = 2> 1 and t _mod / 2M ₀ = t _{pw, ill} are shown. FIG. 4C1 shows the speckle modulator driving waveform, the illumination pulse generator irradiation waveform, the effective modulation amplitude factor M _eff as an index of the speckle reduction effect, and the speckle reduction effect with respect to the elapsed time. The modulation amplitude factor M ₀ = 1 and t _mod / M ₀ = t _{pw, ill} are shown. FIG. 4C2 shows the speckle modulator driving waveform, the illumination pulse generator irradiation waveform, the effective modulation amplitude factor M _eff as an index of the speckle reduction effect, and the speckle reduction effect with respect to the elapsed time. The modulation amplitude factor M ₀ = 2> 1 and t _mod / M ₀ = t _{pw, ill} are shown. FIG. 5 schematically shows an overall configuration of an endoscope system including the imaging system according to the first embodiment. FIG. 6A schematically shows a configuration of a light guide characteristic modulator that changes the optical characteristics of laser light guided by the first optical fiber by vibrating the first optical fiber. FIG. 6B schematically shows a configuration of a light guide characteristic modulator that changes the optical characteristic of the laser light guided by the first optical fiber by rotating the first optical fiber. FIG. 6C schematically shows a configuration of a light guide characteristic modulator that changes the optical characteristic of the laser light by changing the refractive index of the optical path between the collimating lens and the second fiber coupling lens. FIG. 6D schematically shows a configuration of a light guide characteristic modulator that changes the optical characteristic of the laser light by changing the optical path length of the optical path between the collimating lens and the second fiber coupling lens. FIG. 7 schematically shows an overall configuration of an endoscope system including an imaging system according to the second embodiment. FIG. 8A shows an irradiation waveform of an illumination pulse generator, a driving waveform of a speckle modulator, and an effective modulation amplitude factor M _eff as an index of a speckle reduction effect in a single pulse type pulse width modulation method. FIG. 8B shows the irradiation waveform of the illumination pulse generator, the driving waveform of the speckle modulator, and the effective modulation amplitude factor M _eff that serves as an index of the speckle reduction effect in the multiple pulse division type pulse width modulation method. FIG. 9A schematically shows a speckle modulator configured by combining the same two modulators. FIG. 9B schematically shows a speckle modulator configured by combining two modulators having different driving mechanisms but the same optical principle. FIG. 9C schematically shows a speckle modulator configured by combining two modulators having different optical principles. FIG. 10 schematically shows the overall configuration of the illumination apparatus according to the fourth embodiment. FIG. 11 schematically shows the overall configuration of a microscope system including an imaging system according to the fifth embodiment.

[Preparations for discussing the effects of the main forms]
First, before discussing in detail the configuration and requirements for reducing speckle noise, we will discuss a general mechanism for reducing the speckle reduction effect obtained by a lighting device or an imaging system using a modulator of optical characteristics of various laser beams. 1A, 1B, 1C, 2A, 2B, and 2C. In this specification, in order to reduce speckles, the optical characteristics of the emitted light of the light source itself are included, and the optical characteristics in the optical path from the light source to the observation target are changed to change the strength and intensity of the observed speckle pattern. Modulators having various optical characteristics that change the distribution or cause positional changes of the speckle pattern are called “speckle modulators”.

In addition, the magnitude of the speckle modulator driving for causing the modulation of various optical characteristics to obtain the above speckle reduction is defined as “the driving strength of the speckle modulator” and is described as I _mod . Here, as a specific example of “drive intensity of speckle modulator”, the drive intensity of the laser wavelength modulation circuit for causing the effective optical spectrum width expansion or reduction or optical wavelength shift of the laser, observation from the light source In order to change the phase of light when an optical fiber is used as the optical path to guide the observation target from the light source to the observation target, the driving intensity of the phase modulator to cause the change of the phase of the light arranged in the middle of the optical path guided to the target Furthermore, it means the driving strength of a vibration device that generates a mechanical bending change of the optical fiber, the driving strength of a stress application device that changes the stress applied to the optical fiber, the driving strength of a rotating device that generates twisting of the optical fiber, and the like.

1A to 1C illustrate a speckle reduction mechanism by mechanically vibrating an optical fiber in the optical path of laser light from a laser light source to an observation target.

FIG. 1A shows a speckle modulator composed of a vibration device that vibrates an optical fiber. A vibration motor MT is installed on a fixing member (not shown) via a damper DP that absorbs vibration. A weight having a center of gravity which is asymmetric with respect to the rotation axis is attached to the rotation axis of the vibration motor MT. An abutting member TP is fixed to the vibration motor MT. The abutting member TP is in contact with the optical fiber FB. When the rotation shaft of the vibration motor MT rotates, the vibration motor MT vibrates. This vibration is transmitted to the optical fiber FB via the abutting member TP. As a result, the optical fiber FB is vibrated.

Thus, by vibrating the optical fiber FB, the phase and mode of the laser light in the optical fiber FB can be changed with time, and the speckle pattern can be changed with time (FIG. 1B). Within one imaging frame time, the image formed on the imaging surface is observed by overlapping speckle patterns that change over time, so the speckle patterns are averaged and effective on the imaging surface. Speckle noise can be reduced. As shown in FIG. 1B, when the change (or movement amount) of the speckle pattern within the imaging time is sufficiently large and the superposition of the speckle pattern within the imaging time can be regarded as being sufficiently averaged, the vibration is further increased. Even if the amplitude is increased, the speckle reduction effect due to the time average overlap of speckle patterns is considered to be saturated.

FIG. 1C shows a result of an experiment actually conducted by the present inventors. Specifically, FIG. 1C shows a result of measuring an effective speckle contrast change with respect to the vibration amplitude X _{mod, 0} of the optical fiber. Yes. Consistent with what was predicted in connection with FIG. 1B, the vibration amplitude becomes maximum at a certain threshold value ΔX _{mod, th} , and the speckle reduction effect is hardly changed even when the amplitude is increased. Is obtained. In this experiment, speckle contrast is evaluated when imaging is performed with a long imaging time so that the speckle pattern is sufficiently overlapped within the imaging time.

FIG. 2A shows a spectrum of laser light whose wavelength is temporally changed with a fluctuation width λ _mod . FIG. 2B shows a one-dimensional light intensity distribution of a speckle pattern corresponding to the wavelength fluctuation width λ _mod of the laser light shown in FIG. 2A. FIG. 2C shows the change in effective speckle contrast with respect to the change width Δλ _{mod, 0} of the fluctuation width of the wavelength of the laser beam. As shown in FIGS. 2B and 2C, when the fluctuation width λ _mod of the wavelength of the laser light is increased, the light intensity distribution resulting from the speckle phenomenon is reduced (that is, the speckle contrast is reduced). This is because, as a speckle modulator, the wavelength of the laser light is modulated and the wavelength range of the integrated light appears to expand, effectively reducing the coherence of the laser light. It corresponds to that. The threshold Δλ _{mod, th} corresponding to the wavelength change width for saturating the speckle reduction effect is determined by the resolution of the imaging optical system and imager. The reduction effect hardly changes, as in the case of FIGS. 1A to 1C.

In this specification, in order to summarize and discuss the effects of various speckle modulators for speckle reduction in a generalized manner, the speckle modulator drive is used regardless of the speckle modulator for reducing speckle noise. The intensity is I _mod , the drive intensity amplitude is I _{mod, 0,} and the time period when the speckle modulator is periodically driven is the speckle modulation period t _mod . In addition, the speckle modulator drive strength threshold width ΔI _{mod, th} is defined as the width of the drive strength corresponding to the condition that the speckle reduction effect is saturated at a drive strength higher than that. Let ΔI _{mod be} the change width of the drive intensity of the speckle modulator corresponding to the exposure period of the imager within the imaging frame time. (Instead of limiting the pulse emission period _{tpw, ill of the} light source within the imaging frame time, the light amount adjustment by PWM may be performed by limiting the exposure period (or light accumulation period) _{tpw, exp} of the imager. In this case, the change width of the drive intensity during the exposure period _{tpw, exp} becomes ΔI _mod ) Further, the drive intensity amplitude I _{mod, 0} of the speckle modulator is set to the drive intensity threshold width ΔI of the speckle modulator. _{A value} normalized by _{mod, th} is defined as a modulation amplitude factor M ₀ , and a change width ΔI _mod of the speckle modulator drive intensity is defined as ΔI _{mod, th} as an effective modulation amplitude factor M _eff .

According to the above discussion, in general, the speckle modulator is driven at a sufficiently fast cycle with respect to the exposure period t _ON of the imager within one imaging frame or the pulse emission period t _{pw, ill of the} light source. Alternatively, if the imaging timing of the imager, the driving timing of the speckle modulator, and the irradiation timing of the laser beam are optimally synchronized, when the change width ΔI _mod of the driving strength of the speckle modulator is increased, ΔI _mod becomes ΔI Until it becomes _{mod, th} , the speckle reduction effect increases monotonously and saturates in the vicinity where ΔI _mod becomes ΔI _{mod, th} . In addition, if the effective modulation amplitude factor M _eff is increased by increasing the change width ΔI _mod of the driving intensity of the speckle modulator, the speckle reduction effect increases monotonously with M _eff , and a single speckle reduction mechanism Is operated, it is considered that the speckle reduction effect is almost saturated when M _eff ≧ 1.

The driving strength threshold width ΔI _{mod, th} is 0.1 mm as a displacement in vibration of a light guide member changing device (described later) that mechanically changes the optical fiber as the light guide member. The drive intensity amplitude I _{mod, 0} is preferably 0.1 mm or more in terms of the displacement of the vibration of the optical fiber by the light guide member varying device. Since this is about five times the core diameter Φc = 0.02 mm of the optical fiber at the time of the experiment, the driving intensity amplitude I _{mod, 0} of the speckle modulator is 5Φc as the displacement of the optical fiber due to the vibration of the light guide member fluctuation device. The above is considered desirable.

Further, since the driving strength threshold width ΔI _{mod, th} is 10 ° when the optical fiber to be described later is twisted, the driving strength amplitude I _{mod, 0} of the speckle modulator is 10 ° or more when the optical fiber is twisted. It is desirable to be.

In addition, when a refractive index change of a refractive index modulator (electro-optic element, acoustooptic element) described later is used as a speckle modulator, a change corresponding to one wavelength (2π in phase) passes through the refractive index modulator. This is considered to correspond to the drive strength threshold width ΔI _{mod, th} . That is, if the optical wavelength is λ, the length on the optical axis of the refractive index modulator is Lm, the refractive index is n, and the amount of change in the refractive index is Δn, modulation can be performed with Lm · Δn / n / λc ≧ 1. desirable. Therefore, when the length of the refractive index modulator in the light guide direction is Lm, the change in refractive index is Δn / n, and the center wavelength of the spectrum of the illumination pulse is λc, the speckle modulator driving intensity amplitude I _{mod, 0} is refracted. It is desirable that Δn / n ≧ λc / Lm as the refractive index change of the refractive index modulator. As a typical example, if Lm = 5 mm and λc = 0.5 μm, the amount of change in refractive index corresponds to about 0.01%.
[Definition of terms used to discuss the effects of speckle modulators together]

Specifically, the drive intensity of the laser wavelength modulation circuit for expanding the effective optical spectrum width of the laser or shifting the optical wavelength, and the optical phase arranged in the middle of the optical path guided from the light source to the observation target It means the driving strength of the modulator, the mechanical bending strength, applied stress strength, bending strength, etc. for changing the optical phase on the optical path when an optical fiber is used as the optical path guided from the light source to the observation target.

When the speckle modulator is driven periodically, the maximum value of the driving intensity of the speckle modulator is set to I _{mod, max} and the minimum value is set to I _{mod. Let min be} I _{mod, 0} = I _{mod, max} -I _{mod. min} .
<T _mod : speckle modulation period>
This is the time period when the speckle modulator is driven periodically.
<ΔI _mod : Width of change in driving strength of speckle modulator>
In the imaging system, the width of change in the driving intensity of the speckle modulator within the exposure period of the imager (or within the light accumulation period of the imager) within one imaging frame is used. In a lighting device that does not have an imager, the change width of the driving intensity of the speckle modulator is within a time period that is considered to be a response time to an image change of a living body (33 msec if the living body is a human).
<ΔI _{mod, th} : Drive strength threshold width of speckle modulator>
This is the range of change in drive strength for saturating the speckle reduction effect when the drive strength of the speckle modulator is increased.
<M ₀ : Modulation amplitude factor>
M ₀ = I _{mod, 0} / ΔI _{mod, th}
<M _eff : Effective modulation amplitude factor>
M _eff = ΔI _mod / ΔI _{mod, th}
Since M _eff has a positive correlation with the speckle reduction effect, this can be used as an index of the speckle reduction effect. In the case of operating a single speckle reduction mechanism, the speckle reduction effect is almost saturated when M _eff ≧ 1.

3A1 and 3A2, FIG. 3B1 and FIG. 3B2, and FIG. 3C1 and FIG. 3C2 are “the speckle modulator driving amplitude”, “M _eff and speckle reduction effect” with respect to the above-described imaging, illumination, and modulation timings. 3A1 and 3A2 show the case where M ₀ <1, FIGS. 3B1 and 3B2 show the case where M ₀ = 1, and FIGS. 3C1 and 3C2 show the case where M ₀ = 2> 1. Show. 3A1 and 3A2, FIG. 3B1 and FIG. 3B2, and FIG. 3C1 and FIG. 3C2, the upper part shows the driving waveform of the speckle modulator with respect to the elapsed time, and the middle part shows the illumination pulse optimally synchronized with this. The irradiation waveform of the generator is shown on the time axis, and the lower part shows M _{eff as} an index of the speckle reduction effect and the speckle reduction effect with respect to the central time of the irradiation timing of the illumination pulse generator. . Here, M _eff corresponds to the integrated value of the irradiation waveform at the central time of the irradiation timing. Furthermore, Figure 3A1 and Figure 3B1 and Figure 3C1, the pulse width (or pulse emission _period) of the irradiation waveform _{t pw,} if _ill is shorter than half the period of the modulation period of the speckle modulator _{_(t} mod / _2> t _{pw ,} Ill), FIG. 3A2, FIG. 3B2, and FIG. 3C2 show the case where the pulse width of the irradiation waveform (ie, the pulse emission period) t _{pw, ill} is equal to half of the modulation period of the speckle modulator (t _mod / 2 = t _{pw, ill} ). 3A1 and 3A2, 3B1 and 3B2, 3C1 and 3C2, the numerical value of the speckle reduction effect is proportional to the reciprocal of the speckle contrast, and the speckle reduction effect by the speckle modulator is maximum. It is shown normalized by speckle contrast. Therefore, the numerical value of the speckle reduction effect is plotted so as to be 1 under the condition that the reduction effect by the speckle modulator is saturated and maximized.

Through the above description, the exposure timing of the imager is preferably synchronized with the irradiation timing, and the exposure period needs to include at least a part of the irradiation period, preferably all. (It is not always necessary to synchronize. For example _, if there is a relationship in which there are a plurality of irradiation pulses between _{tpw and exp,} a speckle reduction effect can be obtained even if they are not synchronized.)

Conversely, when PWM is applied during the exposure period of the imager, the light emission period tpw _{, ill} of the light source is read as the exposure period _{tpw, exp} of the imager through FIGS. 3A1 and 3A2, 3B1 and 3B2, and 3C1 and 3C2. Thus, the same speckle reduction effect can be obtained. In this case, on the contrary, it is needless to say that t _{pw, ill} needs to include a part or all of t _{pw, exp} .

The same can be said for FIG. 4A1 and FIG. 4A2, FIG. 4B1 and FIG. 4B2, and FIG. 4C1 and FIG.

3A1 and FIG. 3A2, FIG. 3B1 and FIG. 3B2, and FIG. 3C1 and FIG. 3C2 are summarized as follows.
· M ₀ and an increase in the drive amplitude or drive the width of the speckle modulator so as to increase the M _eff, speckle reduction effect is enhanced monotonous.
Speaking on the time axis, the speckle reduction effect is maximized when the speckle modulator and the illumination pulse generator are synchronized so that the change width ΔI _mod of the driving intensity of the speckle modulator is increased.
By setting M _eff ≧ 1, the speckle reduction effect can be maximized by optimizing the timing of imaging, illumination, and modulation. Further, under the condition of M _eff ≧ 1, the speckle reduction effect is saturated, the timing dependency of imaging, illumination, and modulation is small, and a stable speckle reduction effect is obtained.

For this reason, a synchronous controller is provided in order to optimize the drive timing of the speckle modulator, the timing of illumination, and the timing of imaging to increase M _eff and sufficiently bring out the speckle reduction effect. Here, the illumination timing means the temporal timing of the pulse emission period generated by the illumination pulse generator, and the imaging timing means the light reception timing of the imager within one imaging frame.

As a method of performing the synchronous control for optimizing the imaging timing, the illumination timing, and the speckle modulator driving timing described above, 1) the imaging timing is set as the master time, and the illumination timing and speckle are used as the master time. A method of synchronizing the modulator driving timing at a predetermined timing, 2) A method of synchronizing an imaging timing and a speckle modulator driving timing at a predetermined timing with the illumination timing as a master time, and 3) A speckle modulator A method of synchronizing the driving timing as the master time with the imaging timing and the speckle modulator driving timing at a predetermined timing. 4) The system clock of the illumination device or the imaging system as the master time, and the imaging timing. Timing, the timing of the illumination, and a method for synchronizing the driving timing of the speckle modulator is a method diverse synchronization can be applied.

Further, the imaging cycle (frame rate) 1 / f _r , the illumination pulse generation cycle t _p , and the speckle modulator drive cycle t _mod are not necessarily the same as long as they can be synchronized.

Figure 4A1 and Figure 4A2, Figure 4B1 and Figure 4B2, Figure 4C1 and Figure 4C2, the imaging described above, the illumination, the modulation amplitude factor _{M 0} of the timing and speckle modulator of the modulation as a parameter, a modulation rate of "speckle modulator FIG. 4A1 and FIG. 4A2 illustrate the relationship between “M _eff and speckle reduction effect”. FIG. 4A1 and FIG. 4A2 illustrate a case where the modulation rate of the speckle modulator is relatively slow and t _mod / 2M ₀ > t _{pw, ill} . 4B2 shows that when the modulation rate of the speckle modulator is just t _mod / 2M ₀ = t _{pw, ill} , FIGS. 4C1 and 4C2 show that the modulation rate of the speckle modulator is relatively high and t _mod / M ₀ = The case of _{tpw, ill} is shown. 4A1 and 4A2, FIG. 4B1 and FIG. 4B2, and FIG. 4C1 and FIG. 4C2, the upper part shows the driving waveform of the speckle modulator with respect to the elapsed time, and the middle part shows the irradiation waveform of the illumination pulse generator in time. The lower part shows the effective modulation amplitude factor M _eff and the speckle reduction effect as an index of the speckle reduction effect with respect to the irradiation timing of the illumination pulse generator. Here, FIGS. 4A1, 4B1, and 4C1 show the case where the modulation amplitude factor M ₀ = 1 of the speckle modulator, and FIGS. 4A2, 4B2, and 4C2 show that the modulation amplitude factor M ₀ = 2> 1 of the speckle modulator. Shows the case. In FIGS. 4A1 and 4A2, 4B1 and 4B2, and 4C1 and 4C2, the value of the speckle reduction effect is proportional to the reciprocal of the speckle contrast, and the speckle reduction effect by the speckle modulator is maximum. It is shown normalized by speckle contrast. Therefore, the numerical value of the speckle reduction effect is plotted so as to be 1 under the condition that the reduction effect by the speckle modulator is saturated and maximized.

4A1 and 4A2, FIG. 4B1 and FIG. 4B2, and FIG. 4C1 and FIG. 4C2 are summarized as follows.
Even when t _mod > 2M ₀ t _{pw, ill} , the speckle reduction effect can be most efficiently brought out by synchronizing the speckle modulator and the illumination pulse generator. However, when M _eff <1, it cannot be reduced as the speckle reduction effect is saturated.
By driving the speckle modulator with M ₀ ≧ 1, even if the speckle modulator is not driven at a high speed such that t _mod <2t _{pw, ill} , the condition is M ₀ times slower than this (t _mod ≦ 2M _{Even at 0} t _{pw, ill} ), by synchronizing the speckle modulator and the illumination pulse generator, it is possible to bring out the maximum level effect at which the speckle reduction effect is saturated.
・ When speckle modulator is driven at M ₀ ≧ 1 and t _mod ≦ M ₀ t _{pw, ill} , it does not depend much on the timing of synchronous control, and the speckle reduction effect is stable and close to the maximum value. can do.

In the conventional way of thinking that does not consider the concept of the modulation amplitude factor M ₀ , it is considered that the speckle reduction effect cannot be achieved without maximum and temporal fluctuation unless t _mod <t _{pw, ill} , but the speckle is only M ₀ times. Even if the modulation speed of the modulator is decreased (or the pulse emission period is shortened by M ₀ times), the speckle reduction effect can be stabilized and maximized.

As described above, the speckle modulator driving cycle t _mod and timing are greatly affected by the speckle reduction effect by the pulse emission period _{tpw, ill} and its timing in the lighting device. Similarly, in the imaging system having an imager, the speckle reduction effect is greatly affected by the exposure period _{tpw, exp} and the timing of the speckle modulator driving cycle t _mod and timing.

Therefore, in the following embodiments, the pulse emission period is all established even if it is read as either the pulse emission period or the exposure period _{tpw, exp of the} imager or their overlapping portions.

[First Embodiment]
FIG. 5 schematically shows an overall configuration of an endoscope system including the imaging system according to the first embodiment.

The endoscope system 300 includes an endoscope scope unit 310 and an endoscope controller unit 320. The endoscope scope unit 310 and the endoscope controller unit 320 are connected by a scope unit connector 312 and a controller unit connector 322.

The imaging system 100 according to the present embodiment includes the illumination device 102 that illuminates the observation target 190 and the imaging device 104 that captures the observation target 190 illuminated by the illumination device 102.

In FIG. 5, the scope connector 312 and the controller connector 322 that connect the endoscope scope unit 310 and the endoscope controller unit 320 are depicted as one piece, but the endoscope scope unit 310 side of the illumination device 102 is illustrated. The endoscope controller unit 320 side, and the endoscope scope unit 310 side and the endoscope controller unit 320 side of the imaging device 104 may be connected by separate connectors.

The illuminating device 102 includes an illumination light generator 110 that generates illumination light of coherent light, a light guide optical system 120 that guides coherent light emitted from the illumination light generator 110, and a light guide by the light guide optical system 120. A light distribution optical system 140 that adjusts and emits the light distribution of the coherent light that is generated is provided.

The illumination light generator 110 includes a laser light source 112 that emits laser light that is coherent light, and a driver 114 that drives the laser light source 112. For example, the illumination light generator 110 includes an illumination pulse generator that generates illumination pulses of a predetermined pulse emission period _{tpw, ill} of coherent light. In the following description, it is assumed that the illumination light generator 110 is composed of an illumination pulse generator unless otherwise specified.

The light guide optical system 120 includes a first optical fiber 124 and a second optical fiber 130 as light guide members for guiding coherent light. The light guide member is not limited to an optical fiber, and instead, for example, a flexible waveguide may be applied. The light guiding optical system 120 also includes a first fiber coupling lens 122 that couples coherent light emitted from the laser light source 112 to the optical fiber 124, and a collimating lens 126 that collimates the light beam emitted from the first optical fiber 124. , A second fiber coupling lens 128 for coupling the light beam collimated by the collimating lens 126 to the second optical fiber 130 is provided. Although the first fiber coupling lens 122, the collimating lens 126, and the second fiber coupling lens 128 are schematically depicted as one lens in FIG. 5, they are actually composed of one lens. Alternatively, it may be composed of a plurality of lenses.

The imaging device 104 includes an imager 150 that captures images in predetermined exposure periods _{tpw and exp} , an image processing circuit 160 that performs necessary image processing on image information acquired by the imager 150, and an image that is processed by the image processing circuit 160. A display 170 is provided for displaying the processed image.

The laser light emitted from the laser light source 112 is condensed by the first fiber coupling lens 122, enters the first optical fiber 124, and is guided by the first optical fiber 124. The beam of laser light emitted from the first optical fiber 124 is converted into a parallel light beam by the collimating lens 126 and propagates in the space, and is collected by the second fiber coupling lens 128 and condensed by the second optical fiber 130. And is guided by the second optical fiber 130. The laser light guided by the light guide optical system 120 is emitted after the light distribution is adjusted by the light distribution optical system 140. The light L1 emitted from the light distribution optical system 140 is applied to the observation object 190.

The light L1 irradiated to the observation object 190 is reflected, diffracted, scattered, etc. by the observation object 190. A part L 2 of the light reflected, diffracted, scattered, etc. by the observation object 190 enters the imager 150. The imager 150 acquires image information of the observation object 190 based on the light L2 received from the observation object 190. The image information acquired by the imager 150 is displayed on the display 170 after image processing is performed by the image processing circuit 160.

In an imaging system using coherent light, if the observation target has a scattering structure such as slight unevenness, speckles are generated on the imaging surface of the imager and appear as speckle noise in the acquired image. This phenomenon is not limited to an electronic imaging system, but also occurs on the retina of a living body corresponding to the imaging surface, and the same problem occurs in an illumination device using coherent light. The cause of speckle is that light scattered from the unevenness of the observation target interferes, and a fine light-dark pattern is formed on the imaging surface and the retina.

In order to reduce this speckle noise, the illumination device 102 includes a speckle modulator 200 that modulates speckle generated by coherent light.

The speckle modulator 200 may be configured by, for example, a light guide characteristic modulator that changes the optical characteristics of coherent light guided by the light guide optical system 120. Or the speckle modulator 200 may be comprised with the wavelength modulator which changes the optical characteristic of coherent light.

The light guide characteristic modulator may be composed of a phase modulator that temporally changes the phase of coherent light guided by the light guide optical system 120, for example. For example, the phase modulator may include a light guide member changing device that mechanically changes the light guide member included in the light guide optical system 120 that guides coherent light. The mechanical variation applied to the light guide member may be, for example, vibration, rotation, or twist. Alternatively, the phase modulator may be configured by a refractive index modulator that temporally changes the refractive index of a part of the light guide optical system 120 that guides coherent light. The refractive index modulator may include, for example, an electro-optic element or an acousto-optic element. The phase modulator may also include a concavo-convex plate having a concavo-convex greater than 1/10 of the wavelength of the coherent light, for example. Alternatively, the phase modulator may be composed of a wavelength modulator that temporally changes the wavelength of coherent light emitted from the illumination light generator 110.

In the present embodiment, the speckle modulator 200 includes a first light guide characteristic modulator 210 disposed at an intermediate portion between both ends of the first optical fiber 124, and between the collimating lens 126 and the second fiber coupling lens 128. The second light guide characteristic modulator 220 is disposed on the optical path of the collimated light beam. The speckle modulator 200 also includes a wavelength modulator 230 that temporally changes the wavelength of the laser light emitted from the laser light source 112.

The wavelength modulator 230 includes a wavelength-variable laser light source 112 and a wavelength modulation circuit 232 that controls the laser light source 112 so as to temporally change the wavelength of the laser light emitted from the laser light source 112. The configurations of the first light guide characteristic modulator 210 and the second light guide characteristic modulator 220 will be described later with reference to FIGS. 6A to 6D.

The speckle modulator 200 does not necessarily need to include all of the first light guide characteristic modulator 210, the second light guide characteristic modulator 220, and the wavelength modulator 230, and may include at least one of them.

The illumination device 102 also includes a synchronization controller 240 that controls the illumination light generator 110 and the speckle modulator 200 by synchronizing the pulse generation timing of the illumination light generator 110 and the drive timing of the speckle modulator 200. For example, the synchronization controller 240 controls the pulse generation timing of the illumination light generator 110 and the drive timing of the first light guide characteristic modulator 210 and / or the second light guide characteristic modulator 220 in synchronization. Furthermore, the synchronization controller 240 controls the illumination light generator 110, the speckle modulator 200, and the imager 150 by synchronizing the pulse generation timing of the illumination light generator 110, the drive timing of the speckle modulator 200, and the imaging timing of the imager 150. It is also possible.

Even if there is a restriction on the drive intensity amplitude I _{mod, 0} of the speckle modulator 200 and the pulse emission period _{tpw, ill} of the illumination light generator 110, the synchronous controller 240 determines the drive timing of the speckle modulator 200 and the illumination timing. It is provided in order to optimize the timing of imaging and increase M _eff so that the speckle reduction effect can be sufficiently obtained.

Here, the illumination timing means the temporal timing of the pulse emission period generated by the illumination light generator 110, and the imaging timing means the light reception timing of the imager 150 within one imaging frame. To do.

Further, the imaging cycle (frame rate) 1 / f _r , the illumination pulse generation cycle t _p , and the speckle modulator drive cycle t _mod are not necessarily the same as long as they can be synchronized. For example, assuming that n is a natural number, 1 / f _r = 2n · t _p = 2n · t _mod , or t _p = 2n · t _mod , so that the period of each is an integer multiple Applicable. (The case of generating a plurality of illumination pulses in one frame will be described in the second embodiment.)

Here, consider an imaging system, a plurality of illumination pulses are to be distributed in a t _on, the desired effect by a plurality of pulses divided even in the illumination device having no imager (one for naked eye observation) can get. In this case, the effective pulse emission period _{tpw, eff} can be defined as the end point of the last illumination pulse from the start point of the next illumination pulse with the widest pulse interval. In other words, the effective pulse emission period _{tpw, eff} can be said to be a period from the lighting time of the first illumination pulse to the extinguishing time of the last illumination pulse in one illumination pulse group.

6A, FIG. 6B, FIG. 6C, and FIG. 6D show a configuration example of a light guide characteristic modulator that functions as a speckle modulator. Among these, FIG. 6A and FIG. 6B show the structural example of the 1st light guide characteristic modulator 210 arrange | positioned in the intermediate position of an optical fiber, FIG. 6C and FIG. 6D show the collimating lens 126 and the 2nd fiber coupling lens. The example of a structure of the 2nd light guide characteristic modulator 220 arrange | positioned on the optical path between 128 is shown.

FIG. 6A schematically shows the configuration of a light guide characteristic modulator 210A that changes the optical characteristics of the laser light guided by the first optical fiber 124 by vibrating the first optical fiber 124.

The light guide characteristic modulator 210A includes a light guide member changing device 2110 that mechanically changes the first optical fiber 124 that guides laser light, and a driver 2130 that drives the light guide member changing device 2110. Here, the light guide member fluctuation device 2110 is an optical fiber vibration device that applies vibration to the first optical fiber 124. The light guide member varying device 2110 has a vibration motor 2112. The vibration motor 2112 is installed on a damper 2118 that absorbs vibration. The damper 2118 is installed on a fixing member (not shown). A weight 2116 having a center of gravity asymmetric with respect to the rotation shaft 2114 is attached to the rotation shaft 2114 of the vibration motor 2112. An abutting member 2120 is fixed to the vibration motor 2112. The abutting member 2120 is in contact with the first optical fiber 124.

When the vibration motor 2112 is supplied with a current from the driver 2130 via the electric wiring 2140, the rotation shaft 2114 rotates. Since the weight 2116 having an asymmetric center of gravity is attached to the rotation shaft 2114, the vibration motor 2112 vibrates when the rotation shaft 2114 rotates. This vibration is transmitted to the optical fiber 124 via the butting member 2120. As a result, the first optical fiber 124 is vibrated. Thereby, since the bending of the first optical fiber 124 changes periodically, the phase and mode of the laser light guided by the first optical fiber 124 change with time.

In the light guide characteristic modulator 210A, preferably, when the core diameter of the first optical fiber 124 is Φc, the drive intensity amplitude I _{mod, 0} of the light guide characteristic modulator 210A is equal to the first optical fiber 124 by the light guide member fluctuation device 2110. The vibration displacement is 5Φc or more.

Note that the driving intensity amplitude I _{mod, 0} of the light guide characteristic modulator 210A is increased by increasing the rotational speed of the vibration motor 2112 to increase the vibration amplitude X _{mod, 0} by utilizing the increase in centrifugal force. It can be enlarged. Alternatively, if the weight 2116 is attached around the rotation shaft 2114 of the vibration motor 2112 via an elastic member, the weight 2116 increases the rotational speed of the vibration motor 2112 and the asymmetry of the center of gravity of the weight 2116 with respect to the rotation shaft 2114. Is configured to increase. For this reason, when the rotational speed of the vibration motor 2112 is increased, the vibration amplitude further increases.

FIG. 6B schematically shows a configuration of a light guide characteristic modulator 210B that changes the optical characteristics of the laser light guided by the first optical fiber 124 by rotating the first optical fiber 124.

The light guide characteristic modulator 210B includes a light guide member fluctuation device 2150 that applies mechanical fluctuations to the first optical fiber 124 that guides laser light, and a driver 2170 that drives the light guide member fluctuation device 2150. Here, the light guide member fluctuation device 2150 is an optical fiber rotation device that applies reciprocal rotation to the first optical fiber 124. The light guide member varying device 2150 has a rotation motor 2152. The rotary motor 2152 is installed on a fixing member (not shown). A gear 2156 is attached to the rotary shaft 2154 of the rotary motor 2152. The gear 2156 meshes with a gear 2158 fixed to the first optical fiber 124.

When the rotation motor 2152 is supplied with a current from the driver 2170 via the electric wiring 2180, the rotation shaft 2154 reciprocally rotates clockwise and counterclockwise periodically within a predetermined angle range. This reciprocating rotational motion is transmitted to the gear 2158 fixed to the first optical fiber 124 via the gear 2156. As a result, the first optical fiber 124 is reciprocally rotated. As a result, the twist around the axis of the first optical fiber 124 changes periodically, so that the phase and mode of the laser light guided by the first optical fiber 124 change with time.

In the light guide characteristic modulator 210B, the drive intensity amplitude I _{mod, 0} of the light guide characteristic modulator 210B is preferably 10 ° or more in terms of an angle at which the first optical fiber 124 is twisted.

The drive intensity amplitude I _{mod, 0} of the light guide characteristic modulator 210B can be increased by increasing the reciprocal rotation angle of the rotary motor 2152, for example, by increasing the torsion amplitude θ _{mod, 0} .

FIG. 6C schematically shows a configuration of a light guide characteristic modulator 220A that changes the optical characteristic of the laser light by changing the refractive index of the optical path between the collimating lens 126 and the second fiber coupling lens 128. .

The light guide characteristic modulator 220A includes a refractive index modulator 2210 disposed on the optical path between the collimating lens 126 and the second fiber coupling lens 128, and a driver 2220 for driving the refractive index modulator 2210. The refractive index modulator 2210 is an optical element that temporally changes the refractive index of the optical path of the laser light passing therethrough. The refractive index modulator 2210 may be composed of, for example, an electro-optic element. Alternatively, the refractive index modulator 2210 may be composed of an acousto-optic element, for example. The refractive index modulator 2210 includes an optical medium 2212 that transmits laser light, and a drive electrode 2214 provided on the optical medium 2212.

In the refractive index modulator 2210, when an AC voltage is applied from the driver 2220 to the drive electrode 2214 via the electrical wiring 2230, the refractive index of the optical medium 2212 periodically changes over time. As a result, the phase of the laser light passing through the optical medium 2212 changes with time.

In the light guide characteristic modulator 220A, preferably, the length of the refractive index modulator 2210 in the light guide direction is Lm, the change in refractive index is Δn / n, and the center wavelength of the spectrum of the illumination pulse is λc, the light guide characteristic modulator 220A. The drive intensity amplitude I _{mod, 0} is Δn / n ≧ λc / Lm in terms of a change in refractive index of the refractive index modulator 2210.

The drive intensity amplitude I _{mod, 0} of the light guide characteristic modulator 220A can be controlled by the magnitude of the voltage applied to the refractive index modulator 2210.

FIG. 6D schematically shows a configuration of the light guide characteristic modulator 220B that changes the optical characteristic of the laser light by changing the optical path length of the optical path between the collimating lens 126 and the second fiber coupling lens 128. .

The light guide characteristic modulator 220B includes a refractive index modulator 2240 disposed on the optical path between the collimating lens 126 and the second fiber coupling lens 128, and a driver 2260 for driving the refractive index modulator 2240. Refractive index modulator 2240 has a phase difference disk 2250 disposed on the optical path. The phase difference disk 2250 has a concavo-convex pattern 2252 having a concavo-convex greater than 1/10 of the wavelength of the laser beam. The phase difference disk 2250 is supported so as to be rotatable around an axis out of the optical path. A gear 2254 is formed on the outer periphery of the phase difference disk 2250. The refractive index modulator 2240 also has a rotation motor 2242 that rotates the phase difference disk 2250. The rotary motor 2242 is installed on a fixing member (not shown). A gear 2246 is attached to the rotation shaft 2244 of the rotation motor 2242. The gear 2246 meshes with the gear 2254 of the phase difference disk 2250.

When the rotation motor 2242 receives supply of current from the driver 2260 via the electric wiring 2270, the rotation shaft 2244 rotates. This rotational motion is transmitted to the gear 2254 formed on the phase difference disk 2250 via the gear 2246. As a result, the phase difference disk 2250 is rotated, and the concave / convex pattern 2252 moves across the optical path. As a result, the optical path length of the laser light passing through the phase difference disk 2250 periodically changes, so that the phase of the laser light changes with time.

The drive intensity amplitude I _{mod, 0} of the light guide characteristic modulator 220B can be increased by increasing the rotation speed by increasing the voltage applied to the rotary motor 2242.

In the imaging system 100 shown in FIG. 5, when any one of the light guide

characteristic modulators

210A, 210B, 220A, and 220B shown in FIGS. 6A to 6D is mounted as the speckle modulator 200, FIGS. As described with reference to FIGS. 2A to 2C and FIGS. 3A1 to 3C2, operations and effects of the speckle modulator 200 are as follows.
When speckle modulator 200 is increased the variation range [Delta] I _mod drive strength of, [Delta] it _mod is [Delta] I _mod, Until _th continue growing speckle reduction effect, the vicinity of [Delta] I _mod is [Delta] I _mod, the _th Saturates at.
When the value obtained by normalizing the drive intensity change width ΔI _mod of the speckle modulator 200 by Δ _{Imod, th} is defined as an effective modulation amplitude factor M _eff (the drive intensity change width ΔI _mod of the speckle modulator 200 is increased. If it by) increasing the effective modulation amplitude factor _{M eff,} speckle reduction effect increases with _{M _eff,} speckle reduction effect in _{M eff>} 1 is considered substantially saturated.

Also,
· M ₀ and an increase in the drive amplitude or drive the width of the speckle modulator 200 so as to increase the M _eff, increases the speckle reduction effect.
For this reason, when the speckle modulator 200 and the illumination light generator 110 are synchronized so that the change width ΔI _mod of the driving intensity of the speckle modulator 200 is increased, the speckle reduction effect is maximized.
By setting M _eff ≧ 1, the speckle reduction effect can be maximized by optimizing the timing of imaging, illumination, and modulation. Further, under the condition of M _eff ≧ 1, the speckle reduction effect is saturated, the timing dependency of imaging, illumination, and modulation is small, and a stable speckle reduction effect is obtained.

In addition, as described with reference to FIGS. 4A1 to 4C2, the speckle reduction effect is as follows with respect to the driving period t _mod , the pulse emission period t _{pw, ill} , and the modulation amplitude factor M ₀ of the speckle modulator. .
Even in the case of t _mod > 2M ₀ t _{pw, ill} , the speckle reduction effect can be most efficiently brought out by synchronizing the speckle modulator 200 and the illumination light generator 110. However, when M _eff <1, it cannot be reduced as the speckle reduction effect is saturated.
By driving the speckle modulator 200 with M ₀ ≧ 1, even if the speckle modulator 200 is not driven at a high speed such that t _mod <2t _{pw, ill} , a condition that is M ₀ times slower than this (t _mod ≦ 2M ₀ t _{pw, ill} ), by synchronizing the speckle modulator 200 and the illumination light generator 110, it is possible to bring out the maximum level effect that the speckle reduction effect is saturated.
・ Speckle modulator 200 is driven with M ₀ ≧ 1 and t _mod ≦ M ₀ t _{pw, ill} , it does not depend much on the timing of synchronous control, and the speckle reduction effect is almost stable and maximum Can be a value.

As described above, the imaging system 100 according to the present embodiment performs the light amount adjustment by the PWM based on the pulse emission period _{tpw, ill} of the illumination light generator 110, or the PWM based on the _{tpw, exp} of the imager 150. It is also possible to adjust the amount of light.

When performing light quantity adjustment by PWM based on the pulse light emission period _{tpw, ill} of the illumination light generator 110, the imaging system 100 of the present embodiment operates as follows.

The synchronous controller 240 controls the speckle modulator 200 to operate at least in the pulse emission period _{tpw, ill} per illumination pulse.

The speckle modulator 200 periodically changes the driving intensity I _mod of the speckle modulator 200. The drive intensity amplitude I _{mod, 0} of the speckle modulator 200 is preferably set to be equal to or greater than the drive intensity threshold width ΔI _{mod, th} . For example, the drive intensity amplitude I _{mod, 0} of the speckle modulator 200 is equal to or greater than the drive intensity threshold width ΔI _{mod, th} of the drive intensity change width ΔI _mod of the speckle modulator 200 in the pulse emission period _{tpw, ill} . Is set to be

Also, the synchronous controller 240 controls at least the pulse generation timing of the illumination light generator 110 and the driving timing of the speckle modulator 200 in synchronization as follows in order to enhance the speckle reduction effect.

The synchronous controller 240 controls the illumination light generator 110 to generate illumination pulses during the exposure period _{tpw, exp} of the imager 150.

When the pulse light emission period t _{pw, ill} is a period that is less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the pulse light emission period t _{pw, ill} is equal to the drive intensity I _mod of the speckle modulator 200. The illumination light generator 110 and the speckle modulator 200 are controlled so as to include a time when the rate of change is substantially maximum. For example, the synchronous controller 240 is connected to the illumination light generator 110 and the spec so that the center of the pulse emission period t _{pw, ill is} the time when the change rate of the driving intensity I _mod of the speckle modulator 200 is substantially maximized. The modulator 200 is controlled. (Condition A)

_{Alternatively,} when the pulse emission period t _{pw, ill} is a period less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the pulse emission period is t _{pw, ill} and the driving intensity I of the speckle modulator 200 _The illumination light generator 110 and the speckle modulator 200 are controlled so that neither the maximum value nor the minimum value of _mod is included. For example, the synchronous controller 240 includes the illumination light generator so that the pulse emission period t _{pw, ill} includes a time at which the driving intensity I _mod of the speckle modulator 200 takes a value between the substantial maximum value and the minimum value. 110 and speckle modulator 200 are controlled. In particular, the synchronous controller 240 performs illumination so that the center of the pulse emission period t _{pw, ill is} a time at which the driving intensity I _mod of the speckle modulator 200 takes a value between the substantial maximum value and the minimum value. The light generator 110 and the speckle modulator 200 are controlled. (Condition B)

Further, when the pulse emission period t _{pw, ill} is a period of ½ or more of the speckle modulation period t _mod , the synchronous controller 240 determines that the pulse emission period t _{pw, ill} is the driving intensity I of the speckle modulator 200. _The illumination light generator 110 and the speckle modulator 200 are controlled so as to include the time when _mod takes the maximum value and the time when _mod takes the minimum value. (Condition C)

There may be one or more more illumination pulses with different time delays synchronized with the speckle modulator 200. When the pulse emission period is less than ½ of t _mod , it is more preferable to satisfy (Condition A) or (Condition B). For example, if the second illumination pulse comes exactly half a cycle after the first illumination pulse, if the first illumination pulse includes the time at which the slope (absolute value) of the drive intensity I _mod of the speckle modulator 200 is maximum, The second illumination pulse also includes a time at which the slope (absolute value) of the driving intensity I _mod of the speckle modulator 200 becomes maximum (see FIG. 3B1). In the case where the pulse emission period is ½ or more of t _mod , it is more preferable to satisfy (Condition C).

Further, the synchronization controller 240 controls the pulse generation timing of the illumination light generator 110, the drive timing of the speckle modulator 200, and the imaging timing of the imager 150 in synchronization. The synchronous controller 240 drives the speckle modulator 200 and the illumination light generator 110 with M ₀ ≧ 1. Furthermore, the synchronous controller 240 drives the speckle modulator 200 and the illumination light generator 110 with t _mod ≦ 2M ₀ t _{pw, ill} . Alternatively, the synchronous controller 240 drives the speckle modulator 200 and the illumination light generator 110 with t _{pw, ill} <t _mod ≦ M ₀ t _{pw, ill} .

The above is a description of the operation in the case where the light amount adjustment by PWM is performed based on the pulse light emission period _{tpw, ill} of the illumination light generator 110. Instead of this, the PWM is performed based on the t _{pw, exp} of the imager 150. When performing light quantity adjustment, the imaging system 100 of this embodiment operates as follows. In this case, the illumination light generator 110 does not necessarily need to be composed of an illumination pulse generator that generates illumination pulses having a predetermined pulse emission period _{tpw, ill} of coherent light.

The synchronous controller 240 controls the speckle modulator 200 to operate at least in the exposure period _{tpw, exp} .

The speckle modulator 200 periodically changes the driving intensity I _mod of the speckle modulator. The drive intensity amplitude I _{mod, 0} of the speckle modulator 200 is set to be equal to or greater than the drive intensity threshold width ΔI _{mod, th} . For example, the driving intensity amplitude I _{mod, 0} of the speckle modulator 200 has a value that is greater than or equal to the driving intensity threshold width ΔI _{mod, th} of the driving intensity change width ΔI _mod of the speckle modulator 200 in the exposure period _{tpw, exp} . Is set as follows.

The synchronization controller 240 controls at least the imager 150 and the speckle modulator 200 in synchronization as follows in order to enhance the speckle reduction effect.

When the exposure period t _{pw, exp} is a period that is less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the exposure period t _{pw, exp} is the rate of change of the driving intensity I _mod of the speckle modulator 200. The imager 150 and the speckle modulator 200 are controlled so as to include the time at which becomes substantially maximum. For example, the synchronous controller 240 sets the imager 150 and the speckle modulator 200 so that the center of the exposure period t _{pw, exp} is the time when the change rate of the driving intensity I _mod of the speckle modulator 200 is substantially maximized. Control.

_{Alternatively,} when the exposure period t _{pw, exp} is a period that is less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the exposure period t _{pw, exp} is equal to the drive intensity I _mod of the speckle modulator 200. The imager 150 and the speckle modulator 200 are controlled so that neither the maximum value nor the minimum value is included. For example, the synchronous controller 240 may use the imager 150 and the speckle so that the exposure period t _{pw, exp} includes a time at which the driving intensity I _mod of the speckle modulator 200 takes a value between the substantial maximum value and the minimum value. The modulator 200 is controlled. In particular, the synchronization controller 240 sets the imager 150 so that the center of the exposure period t _{pw, exp} is the time at which the driving intensity I _mod of the speckle modulator 200 takes a value between the substantial maximum value and the minimum value. And the speckle modulator 200 is controlled.

When the exposure periods _{tpw, exp} are ½ or more of the speckle modulation period _tmod , the synchronous controller 240 determines that the exposure period _{tpw, exp} is a drive intensity I _mod of the speckle modulator 200. The imager 150 and the speckle modulator 200 are controlled so as to include the time for taking the maximum value and the time for taking the minimum value.

In the imaging system 100 of the present embodiment, speckle noise can be stably and effectively reduced by the operation of the above-described configuration. In addition, a configuration for reducing speckle noise stably and effectively can be added to an existing lighting device or imaging system without incurring a large cost. Even if the drive intensity amplitude I _{mod, 0 of} the speckle modulator 200 and the pulse emission period _{tpw, ill} of the illumination light generator 110 are limited, the drive timing, illumination timing, and imaging timing of the speckle modulator 200 are limited. By optimizing and increasing M _eff , it is possible to sufficiently bring out the speckle reduction effect. In particular, when shooting at a high imaging frame rate, when shooting instantaneously in a short time, or when dimming with a pulse width modulation (PWM) method, a short exposure period or a short pulse per imaging frame is required. Speckle noise can be stably and effectively reduced even during the light emission period.

In conventional imaging systems, the speckle reduction method by mechanically changing the optical fiber cannot fully exhibit the speckle pattern overlapping effect when the imaging frame rate is fast or when the imaging time is short. It is predicted. As a typical example, 60 fps imaging frame rate f _r of the imaging system, the about half of the time corresponding to the inverse of the imaging frame rate and exposure period t _on per imaging frame of the imager, the imager per imaging frame The exposure period t _{pw, exp} is about t _{pw, exp} ≦ t _on = 1/2 × 1/60 sec = 8.3 msec, and it is necessary to mechanically change the shape and stress of the optical fiber at a faster cycle. it is conceivable that. Also, when exposure is required in a shorter time (when high-speed shooting is required), it is difficult to obtain an averaging effect due to speckle pattern overlap due to mechanical vibration speed limitations. Is expected.

Furthermore, when the light amount is adjusted by pulse width modulation (PWM) frequently used in an illumination device using laser light _, the minimum value of the pulse light emission period (or irradiation pulse width) _{tpw, ill} of the light source is This is a period obtained by dividing the exposure period _{tpw, exp} per imaging frame by the number of dimming divisions. For example, assuming a dimming range of 30 dB, the minimum pulse emission period (or irradiation pulse width) t _{pw, ill} (= t _{pw, exp} ) is about 8.3 msec / 1000 = 8.3 μsec. It seems difficult to realize a mechanical vibration period corresponding to.

Further, when viewed visually, the temporal response time of the eyes can be regarded as the exposure period _{tpw, exp} per imaging frame of the imager _, and for a time shorter than approximately 1/30 second (30 fps (frame / second). )) Needs to finish the speckle overlay. Further, considering the dimming by PWM as the dimming method of illumination, for the same reason as described above, a more severe requirement for the driving cycle of the mechanical vibration cycle occurs.

On the other hand, the imaging system 100 of the present embodiment can sufficiently bring out the speckle reduction effect by optimizing the driving timing of the speckle modulator 200, the timing of illumination, and the timing of imaging to increase M _eff. Therefore, it is possible to respond to such a request. In other words, when shooting at a high imaging frame rate, when shooting instantaneously for a short time, or when dimming with a pulse width modulation (PWM) method, a short exposure period or a short pulse per imaging frame is required. Speckle noise can be stably and effectively reduced even during the light emission period.

[Second Embodiment]
FIG. 7 schematically shows an overall configuration of an endoscope system including an imaging system according to the second embodiment. In FIG. 7, members denoted by the same reference numerals as those shown in FIG. 5 are similar members, and detailed description thereof is omitted. In the following, explanation will be given with emphasis on the different parts. That is, the part which is not touched by the following description is the same as that of 1st Embodiment.

The imaging system 100A according to the present embodiment is different from the imaging system 100 according to the first embodiment in the illumination device 102A. In the illumination device 102A, the illumination light generator 110 repeatedly generates one illumination pulse group including a plurality of illumination pulses as an illumination pulse group sequence. For example, the number of the plurality of illumination pulses included in one illumination pulse group is 3 or more.

The period from the lighting time of the first lighting pulse to the lighting time of the last lighting pulse in one lighting pulse group is defined as an effective pulse emission period. At this time, the effective pulse emission period is, for example, a period twice or more as long as the net pulse emission period of a plurality of illumination pulses included in one illumination pulse group.

In order to control the illumination light generator 110 in this way, the illumination device 102 A includes a pulse width modulation (PWM) light controller 250. The pulse width modulation type light controller 250 adjusts the effective amount of illumination light by controlling the pulse width of a plurality of illumination pulses in the effective pulse emission period _{tpw, eff} . The pulse width modulation type light controller 250 _divides the pulse emission period _tpw corresponding to the desired light control amount into a plurality of pulse emission periods _{tpw, ill, 1} , _... , _{tpw, ill, n} (n is 2 or more). A multiple pulse division type pulse width modulation type optical controller. Here, n represents the number of a plurality of illumination pulses included in one illumination pulse group. Further, the pulse emission period _{tpw, ill, i} (i = 1,..., N) represents the emission period of the i-th illumination pulse included in one illumination pulse group.

In other words, the illuminating device 102A has a configuration in which a multi-pulse division type pulse width modulation light controller 250 is added to the illuminating device 102 according to the first embodiment. The pulse width modulation type light controller 250 controls the driver 114 of the illumination light generator 110 based on a signal input from the synchronization controller 240.

Compared with the well-known “single pulse type pulse width modulation method” (FIG. 8A), the “multiple pulse division type pulse width modulation method” (FIG. 8B) will be described. FIGS. 8A and 8B show the irradiation waveform of the illumination pulse generator, the driving waveform of the speckle modulator, and the effective modulation amplitude factor M _eff that serves as an indicator of the speckle reduction effect in each pulse width modulation method.

"Single Pulse pulse-width modulation method", as shown in the upper part of FIG. 8A, the time of the exposure period t _on, corresponding duration of the illumination pulse (or referred to as period) to the desired amount In this method, the amount of illumination light is adjusted so that the pulse emission period _{tpw, ill} is _reached .

On the other hand, as shown in the upper part of FIG. 8B, the “multiple pulse division type pulse width modulation method” proposed in the present application is divided into a plurality of pulses such that t _{pw, ill} = Σt _{pw, ill, i.} In this way, the amount of illumination light is adjusted.

As shown in the middle part of FIG. 8A and the middle part of FIG. 8B, even if the drive waveform of the speckle modulator is the same, as shown in the lower part of FIG. 8A, in the “single pulse type pulse width modulation method”, ΔI _Mod decreases in proportion to the pulse emission period t _{pw, ill,} and thus M _eff also decreases. As shown in the lower part of FIG. 8B, “multiple pulse division type pulse width modulation method” In this case, by dispersing the emission timing of the irradiation pulse, the effective pulse emission period is expanded even if the pulse emission period _{tpw, ill} is reduced in order to reduce the irradiation light amount. , Effective ΔI _mod (this is ΔI _{mod, eff} ) can be enlarged. For this reason, it is possible to effectively increase the effective modulation amplitude factor M _eff that serves as a speckle reduction index.

When the time width for passing a plurality of illumination pulses within the exposure possible period t _on is an effective pulse emission period _{tpw, eff} , the “multiple pulse division type pulse width modulation optical controller” It functions as an “effective pulse emission period expander” that effectively expands. Here, the concept of “effective pulse light emission period expander” is that the effective pulse light emission period can be expanded by dividing the illumination pulse in time, without adjusting the light amount as described above. This is a concept larger than the concept of “multiple pulse division type pulse width modulation optical controller”.

When using an “effective pulse emission period expander” or “multiple pulse division type pulse width modulation optical controller”, ΔI _{mod, eff} and t _{pw, eff} are increased for the synchronous controller 240. Thus, it is desirable to set the time interval of illumination pulses and the timing of illumination pulses.

It operates as below the imaging system 100A of this embodiment.

The synchronous controller 240 controls the speckle modulator 200 to operate at least during an effective pulse emission period.

Further, the synchronization controller 240 controls the pulse generation timing of the illumination light generator 110, the drive timing of the speckle modulator 200, and the imaging timing of the imager 150 in synchronization. For example, the synchronous controller 240 controls the illumination light generator 110 to generate illumination pulses during the exposure period (t _{pw, exp} ) of the imager 150.

The speckle modulator 200 periodically changes the driving intensity I _mod of the speckle modulator. The drive intensity amplitude I _{mod, 0} of the speckle modulator 200 is preferably set to be equal to or greater than the drive intensity threshold width ΔI _{mod, th} . For example, the driving intensity amplitude I _{mod, 0} of the speckle modulator 200 is equal to or larger than the driving intensity threshold width ΔI _{mod, th} of the driving intensity change width ΔI _mod of the speckle modulator 200 in the effective pulse emission period _{tpw, eff} . Is set to be the value of.

Also, the synchronous controller 240 controls at least the illumination light generator 110 and the speckle modulator 200 in synchronization as follows in order to enhance the speckle reduction effect.

When the effective pulse emission period t _{pw, eff} is a period less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the effective pulse emission period t _{pw, eff} is the speckle modulator drive. The illumination light generator 110 and the speckle modulator 200 are controlled so as to include the time at which the rate of change of the intensity I _mod is maximized. For example, the synchronous controller 240 may connect the illumination light generator 110 and the speckle so that any one of the plurality of illumination pulses includes a time at which the change rate of the speckle modulator driving intensity I _mod is maximum. The modulator 200 is controlled. Alternatively, the synchronous controller 240 may _connect the illumination light generator 110 and the speckle so that the center of the effective pulse emission period t _{pw, eff} is the time at which the rate of change of the speckle modulator driving intensity I _mod is maximized. The modulator 200 is controlled. (Condition D)

Alternatively, when the effective pulse emission period t _{pw, eff} is a period that is less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the effective pulse emission period t _{pw, eff} is the speckle. The illumination light generator 110 and the speckle modulator 200 are controlled so that neither the maximum value nor the minimum value of the modulator driving intensity I _mod is included. (Condition E)

Alternatively, when the effective pulse emission period t _{pw, eff} is a period that is less than ½ of the speckle modulation period t _mod , the synchronous controller 240 determines that the effective pulse emission period t _{pw, eff} is the speckle. The illumination light generator 110 and the speckle modulator 200 are controlled so as to include the time at which the center value of the maximum value and the minimum value of the driving intensity I _mod of the modulator is included. For example, the synchronous controller 240 may determine that one of the plurality of illumination pulses included in one illumination pulse group is the center of the substantial maximum value and minimum value of the driving intensity I _mod of the speckle modulator 200. The illumination light generator 110 and the speckle modulator 200 are controlled so as to include the time when the value is taken. Alternatively, the synchronization controller 240 is set so that the center of the effective pulse emission period t _{pw, eff} is a time at which the center of the substantial maximum value and the minimum value of the driving intensity I _mod of the speckle modulator 200 is taken. The illumination light generator 110 and the speckle modulator 200 are controlled. (Condition F)

In addition, when the effective pulse emission period t _{pw, eff} is a period of ½ or more of the speckle modulation period t _mod , the synchronous controller 240 determines that the effective pulse emission period t _{pw, eff} is a speckle. The illumination light generator 110 and the speckle modulator 200 are controlled so as to include a time for taking the maximum value and a time for taking the minimum value of the driving intensity I _mod of the modulator. (Condition G)

There may be one or more more illumination pulses with different time delays synchronized with the speckle modulator 200. When the effective pulse emission period is less than 1/2 of t _mod , it is more preferable to satisfy (Condition D), (Condition E), or (Condition F). For example, when the second illumination pulse group comes exactly half a cycle after the first illumination pulse group, the time at which the slope (absolute value) of the drive intensity I _mod of the speckle modulator 200 is maximized is the first illumination pulse group. If included, the second illumination pulse group also includes a time at which the slope (absolute value) of the driving intensity I _mod of the speckle modulator 200 becomes maximum. When the effective pulse emission period is 1/2 or more of t _mod , it is more preferable to satisfy (Condition G).

Further, the synchronization controller 240 controls the pulse generation timing of the illumination light generator 110, the drive timing of the speckle modulator 200, and the imaging timing of the imager 150 in synchronization. The synchronous controller 240 drives the speckle modulator 200 and the illumination light generator 110 with M ₀ ≧ 1. Furthermore, the synchronous controller 240 drives the speckle modulator 200 and the illumination light generator 110 with t _mod ≦ 2M ₀ t _{pw, eff} . Alternatively, the synchronous controller 240 drives the speckle modulator 200 and the illumination light generator 110 with t _{pw, eff} <t _mod ≦ M ₀ t _{pw, eff} .

[Third Embodiment]
In the first embodiment (FIG. 5) and the second embodiment (FIG. 7), the speckle modulator 200 is at least one of the first light guide characteristic modulator 210, the second light guide characteristic modulator 220, and the wavelength modulator 230. Although it may be configured, it may be configured by combining them.

An example of the speckle modulator 200 configured by combining two speckle modulators is shown in FIGS. 9A, 9B, and 9C. The effect of speckle reduction by these combinations is as follows.

FIG. 9A schematically shows a speckle modulator 200 configured by combining the same two speckle modulators M1 in terms of the driving mechanism and the optical principle. The speckle modulator M1 is configured to apply vibration to the first optical fiber 124. In FIG. 9A, each speckle modulator M1 is typically depicted as the light guide characteristic modulator 210A shown in FIG. 6A.

When the same two speckle modulators M1 are combined, if the effective modulation amplitude factor for each light guide characteristic modulator 210A is M _{eff, 1} , M _{eff, 2} , the overall speckle reduction effect M _{eff, total} is Because the change in speckle pattern caused by each light guide characteristic modulator 210A is the same,
If M _{eff, 1} + M _{eff, 2} <1, then M _{eff, total} = M _{eff, 1} + M _{eff, 2}
When M _{eff, 1} + M _{eff, 2} ≧ 1, M _{eff, total} = 1
It becomes. This configuration is effective when the speckle reduction effect is insufficient with one speckle modulator M1.

FIG. 9B schematically shows a speckle modulator 200 configured by combining two speckle modulators M1 and M2 having different driving mechanisms but the same optical principle. The speckle modulator M1 is as described above. The speckle modulator M2 is configured to rotate the first optical fiber 124. In FIG. 9B, the speckle modulator M2 is typically depicted as the light guide characteristic modulator 210B shown in FIG. 6B.

Also in this case, since the temporal superposition effect of the light and dark patterns by speckles is used, it is an optically combined configuration of speckle modulators M1 and M2 of the same type. Basically, as in FIG. 9A, There is an effect observed by adding an effective modulation amplitude factor. However, the light and dark pattern pattern due to speckles caused by the speckle modulators M1 and M2 may change differently. For this reason, due to the effect of overlapping various bright and dark pattern patterns, the speckle reduction effect is often stronger (that is, M _{eff, total} > 1) than in the configuration example of FIG. 9A.

FIG. 9C schematically shows a speckle modulator 200 configured by combining two speckle modulators M1 and M3 having different optical principles. The speckle modulator M1 is as described above. The speckle modulator M3 is configured to change the wavelength of the laser light with time. In FIG. 9C, the speckle modulator M3 is depicted as the wavelength modulator 230 shown in FIG.

Two speckle modulators M1 and M3 having different optical principles are connected in series. In this case, since the speckle reduction caused to optical principles _{_{different, M eff, 1 + M eff}} , 2 of regardless of the _size, M _eff, the _{_{total = M eff, 1 + M}} eff, 2.

In addition, about the structure of FIG. 9A, FIG. 9B, and FIG. 9C, the effect of the synchronous controller 240 grade | etc., Is the same as that of 1st Embodiment and 2nd Embodiment.

[Fourth Embodiment]
FIG. 10 schematically shows the overall configuration of the illumination apparatus according to the fourth embodiment. 10, members denoted by the same reference numerals as those shown in FIG. 5 and FIG. 7 are similar members, and detailed description thereof is omitted.

The illumination device 102B according to the present embodiment includes an illumination light generator 110, a light guide optical system 120B that guides laser light emitted from the illumination light generator 110, and a laser guided by the light guide optical system 120B. An irradiation optical system 140B for irradiating light is provided.

The light guide optical system 120B includes a collimating lens 122B that collimates the light beam emitted from the illumination light generator 110, and a coupling lens 124B that couples the light beam collimated by the collimating lens 122B to the irradiation optical system 140B. . The collimating lens 122B and the coupling lens 124B are schematically illustrated as one lens in FIG. 10, but may actually be configured by one lens or may be configured by a plurality of lenses. It may be.

The lighting device 102B also includes a speckle modulator 200, a synchronization controller 240, and a pulse width modulation type light controller 250. The speckle modulator 200 includes a light guide characteristic modulator 220 and a wavelength modulator 230. The light guide characteristic modulator 220 is disposed on the optical path of the collimated light beam between the collimating lens 122B and the coupling lens 124B.

Details of the speckle modulator 200, the light guide characteristic modulator 220, the wavelength modulator 230, and the synchronization controller 240 are as described in the first embodiment, and details of the pulse width modulation type optical controller 250 are described in the second embodiment. As explained.

In the illuminating device 102B that does not have an imager, the change width of the drive intensity of the speckle modulator 200 is speckle within a time period that is considered to be a response time with respect to a change in the image of the living body (about 33 msec when the living body is a human). By considering the change width of the driving intensity of the modulator 200, the observer can obtain the same speckle reduction effect as that of the first to third embodiments.

[Fifth Embodiment]
FIG. 11 schematically shows the overall configuration of a microscope system including an imaging system according to the fifth embodiment. In FIG. 11, members having the same reference numerals as those shown in FIG. 5 and FIG. 7 are similar members, and detailed description thereof is omitted.

The imaging system 100 C according to the present embodiment includes an illumination device 102 C that illuminates the observation object 190 and the imaging device 104.

The illumination device 102C includes an illumination light generator 110, a light guide optical system 120C that guides laser light emitted from the illumination light generator 110, and illumination that emits laser light guided by the light guide optical system 120C. An optical system 300 is provided.

The light guide optical system 120C couples the optical fiber 126C that guides the laser light, the collimator lens 122C that collimates the light beam emitted from the illumination light generator 110, and the light beam collimated by the collimator lens 122C to the optical fiber 126C. A fiber coupling lens 124C is provided. The collimating lens 122C and the fiber coupling lens 124C are schematically illustrated as one lens in FIG. 11, but may actually be configured by one lens or may be configured by a plurality of lenses. May be.

The illumination optical system 300 includes a collimating optical system 310 that collimates the light beam emitted from the optical fiber 126C, a beam splitter 320 that splits the light beam collimated by the collimating optical system 310 into two light beams, and a beam splitter 320. The first mirror 330A that reflects one of the light beams divided by the first mirror 330A and the first light beam that is reflected by the first mirror 330A toward the observation object 190 placed on the sample stage 350 from below. Irradiation optical system 340A, the second mirror 330B that reflects the other light beam split by the beam splitter 320, and the light beam reflected by the second mirror 330B toward the observation object 190 from above obliquely. The second irradiation optical system 340B is provided.

The illumination device 102 C also includes a speckle modulator 200, a synchronization controller 240, and a pulse width modulation type light controller 250. The speckle modulator 200 includes a first light guide characteristic modulator 210, a second light guide characteristic modulator 220, and a wavelength modulator 230. The second light guide characteristic modulator 220 is disposed on the optical path of the collimated light beam between the collimating lens 122C and the fiber coupling lens 124C. The first light guide characteristic modulator 210 is disposed in the middle part of the optical fiber 126C.

The details of the speckle modulator 200, the first light guide characteristic modulator 210, the second light guide characteristic modulator 220, the wavelength modulator 230, and the synchronous controller 240 are as described in the first embodiment, and the pulse width modulation method. Details of the light controller 250 are as described in the second embodiment.

The imaging system 100 C also includes an objective optical system 360 disposed to face the sample stage 350, a lens barrel 370 that supports the objective optical system 360, and an eyepiece and imaging optical system 380 attached to the lens barrel 370. .

The laser light emitted from the light guiding optical system 120C is split into two light beams by the beam splitter 320 through the collimating optical system 310. One light beam is reflected by the first mirror 330A, and is irradiated from below onto the observation object 190 via the first irradiation optical system 340A. Further, the other light beam is reflected by the second mirror 330B, and is irradiated on the observation object 190 from obliquely above via the second irradiation optical system 340B.

The light irradiated on the observation object 190 is reflected, diffracted, scattered, etc. by the observation object 190. A part of the light reflected, diffracted, scattered, etc. by the observation object 190 enters the objective optical system 360. The light incident on the objective optical system 360 is imaged on the light receiving surface of the imager 150 via the eyepiece and the imaging optical system 380, for example, and image information of the observation object 190 is acquired by the imager 150. The image information acquired by the imager 150 is displayed on the display 170 after image processing is performed by the image processing circuit 160. Alternatively, the light incident on the objective optical system 360 is imaged on the retina of the observer via the eyepiece and the imaging optical system 380, and the image of the observation object 190 is observed by the observer.

In the microscope system including the imaging system 100C according to the present embodiment, the operations and effects related to speckle reduction are the same as the operations and effects obtained in the first to fourth embodiments.

[Summary]
Summarizing the above, the present specification discloses an illumination device and an imaging system listed below. In other words, the embodiment described above can be generalized as shown below.

[1] An illumination pulse generator that generates an illumination pulse of coherent light;
A speckle modulator that modulates speckle generated by the coherent light;
An illumination apparatus comprising: a synchronous controller that controls the pulse generation timing of the illumination pulse generator and the drive timing of the speckle modulator in synchronization.

[2] The illumination device according to [1], wherein the synchronous controller controls the speckle modulator to operate in at least a pulse emission period (t _{pw, ill} ) per one illumination pulse.

[3] The illumination device according to [2], wherein the speckle modulator periodically changes a driving intensity (I _mod ) of the speckle modulator.

[4] When the pulse emission period (t _{pw, ill} ) is a period of less than ½ of the speckle modulation period (t _mod ), the synchronous controller has the pulse emission period (t _{pw, ill} ) The illumination device according to [3], wherein the illumination pulse generator and the speckle modulator are controlled so as to include a time at which a change rate of the drive intensity (I _mod ) of the speckle modulator is substantially maximized.

[5] The synchronous controller may be configured such that the center of the pulse emission period (t _{pw, ill} ) is a time at which a change rate of the driving intensity (I _mod ) of the speckle modulator is substantially maximized. The illumination device according to [4], which controls an illumination pulse generator and the speckle modulator.

[6] When the pulse emission period (t _{pw, ill} ) is a period less than ½ of the speckle modulation period (t _mod ), the synchronous controller has the pulse emission period (t _{pw, ill} ). The illumination device according to [3], wherein the illumination pulse generator and the speckle modulator are controlled so that neither the maximum value nor the minimum value of the driving intensity (I _mod ) of the speckle modulator is included.

[7] In the synchronous controller, the pulse emission period (t _{pw, ill} ) includes a time at which the driving intensity (I _mod ) of the speckle modulator takes a value between the substantial maximum value and the minimum value. The illumination device according to [6], wherein the illumination pulse generator and the speckle modulator are controlled.

[8] The synchronous controller may be configured such that the center of the pulse emission period (t _{pw, ill} ) is a time at which the driving intensity (I _mod ) of the speckle modulator takes a substantial center value between a maximum value and a minimum value. The illumination device according to [7], wherein the illumination pulse generator and the speckle modulator are controlled.

[9] When the pulse emission period (t _{pw, ill} ) is a period that is ½ or more of the speckle modulation period (t _mod ), the synchronous controller has the pulse emission period (t _{pw, ill} ) The illumination device according to [3], wherein the illumination pulse generator and the speckle modulator are controlled such that the drive intensity (I _mod ) of the speckle modulator includes a time at which a maximum value and a time at which a minimum value is taken. .

[10] The speckle modulator includes a first speckle modulator and a second speckle modulator, and the synchronous controller includes a pulse generation timing of the illumination pulse generator, the first speckle modulator, and / or Or the illuminating device as described in [1] controlled in synchronization with the drive timing of the second speckle modulator.

[11] When the change range of the drive intensity of the speckle modulator, in which the reduction of the speckle is saturated with respect to the change of the drive intensity of the speckle modulator, is the drive intensity threshold width (ΔI _{mod, th} ), The driving intensity amplitude (I _{mod, 0} ) of the modulator is set to a driving intensity threshold (ΔI _{mod, th} ) or more, [2].

[12] The drive intensity amplitude (I _{mod, 0} ) of the speckle modulator is such that the change width (ΔI _mod ) of the drive intensity of the speckle modulator in the pulse emission period (t _{pw, ill} ) is the drive intensity threshold. The illumination device according to [11], which is set to have a value equal to or greater than (ΔI _{mod, th} ).

[13] The illumination device according to [1] or [2], wherein the speckle modulator includes a phase modulator that temporally changes a phase of the coherent light.

[14] The illumination device according to [13], wherein the phase modulator includes a light guide member changing device that mechanically changes a light guide member included in a light guide optical system that guides the coherent light.

[15] The illumination device according to [13], wherein the phase modulator has a concavo-convex plate having a concavo-convex greater than 1/10 of the wavelength of the coherent light.

[16] The illumination device according to [13], wherein the phase modulator is a refractive index modulator that temporally changes a refractive index of a light guide optical system that guides the coherent light.

[17] The illumination device according to [16], wherein the refractive index modulator includes at least one of an electro-optic element and an acousto-optic element.

[18] When the light guide optical system includes an optical fiber, and the core diameter of the optical fiber is Φc, the drive intensity amplitude (I _{mod, 0} ) of the speckle modulator is the vibration of the optical fiber by the light guide member fluctuation device. The illumination device according to [14], wherein the displacement is 5Φc or more.

[19] The illumination device according to [14], wherein the light guide optical system includes an optical fiber, and a driving intensity amplitude (I _{mod, 0} ) of the speckle modulator is 10 ° or more in terms of an angle at which the optical fiber is twisted.

[20] When the length of the refractive index modulator in the light guide direction is Lm, the change in refractive index is Δn / n, and the center wavelength of the spectrum of the illumination pulse is λc, the driving intensity amplitude (I _{mod, 0} ) is the illumination device according to [16], wherein Δn / n ≧ λc / Lm in terms of a change in refractive index of the refractive index modulator.

[21] An imaging system including the illumination device according to any one of [2] to [12] and an imager that performs imaging in a predetermined exposure period (t _{pw, exp} ).

[22] The imaging system according to [21], wherein the synchronous controller controls the pulse generation timing of the illumination pulse generator, the driving timing of the speckle modulator, and the imaging timing of the imager in synchronization.

[23] The synchronous controller controls the pulse generation timing of the illumination pulse generator, the driving timing of the speckle modulator, and the imaging timing of the imager in synchronization, and in the exposure period (t _{pw, exp} ) of the imager The imaging system according to [21], wherein the illumination pulse generator is controlled to generate the illumination pulse.

[24] The synchronous controller synchronizes and controls the pulse generation timing of the illumination pulse generator, the drive timing of the speckle modulator, and the imaging timing of the imager,
Drive intensity amplitude (I _{mod, 0} ) of the speckle modulator,
The change width of the drive strength of the speckle modulator that the speckle reduction is saturated with respect to the drive strength change of the speckle modulator is a drive strength threshold width (ΔI _{mod, th} ),
The pulse emission period ( _{tpw, ill} ) of the illumination pulse generated by the illumination pulse generator;
For the modulation period (t _mod ) when the speckle modulator is driven periodically,
When M ₀ = I _{mod, 0} / ΔI _{mod, th} ,
The imaging system according to [21], wherein the synchronous controller drives the speckle modulator and the illumination pulse generator with M ₀ ≧ 1 and further drives with t _mod ≦ 2M ₀ t _{pw, ill} .

[25] The synchronous controller controls the pulse generation timing of the illumination pulse generator, the drive timing of the speckle modulator, and the imaging timing of the imager in synchronization with each other,
Drive intensity amplitude (I _{mod, 0} ) of the speckle modulator,
The change width of the drive strength of the speckle modulator that the speckle reduction is saturated with respect to the drive strength change of the speckle modulator is a drive strength threshold width (ΔI _{mod, th} ),
The pulse emission period ( _{tpw, ill} ) of the illumination pulse generated by the illumination pulse generator;
For the modulation period (t _mod ) when the speckle modulator is driven periodically,
When M ₀ = I _{mod, 0} / ΔI _{mod, th} ,
The synchronous controller, the lighting pulse generator and the speckle modulator driven at _{M 0} ≧ 1, _{further, t pw,} imaging according to _{_{_{ill <t mod ≦ M 0 t}}} pw, driven by _ill [21] system.

[26] The imaging system according to [21], wherein the speckle modulator includes a phase modulator that temporally changes the phase of the coherent light.

[27] The imaging system according to [26], wherein the phase modulator includes a light guide member variation device that mechanically varies a light guide member included in a light guide optical system that guides the coherent light.

[28] The imaging system according to [26], wherein the phase modulator has a concavo-convex plate having a concavo-convex greater than 1/10 of the wavelength of the coherent light.

[29] The imaging system according to [26], wherein the phase modulator is a refractive index modulator that temporally changes a refractive index of a light guide optical system that guides the coherent light.

[30] The imaging system according to [29], wherein the refractive index modulator includes at least one of an electro-optic element and an acousto-optic element.

[31] When the light guide optical system includes an optical fiber, and the core diameter of the optical fiber is Φc, the drive intensity amplitude (I _{mod, 0} ) of the speckle modulator is the vibration of the optical fiber by the light guide member fluctuation device. The imaging system according to [27], wherein the displacement is 5Φc or more.

[32] The imaging system according to [27], wherein the light guide optical system includes an optical fiber, and a driving intensity amplitude (I _{mod, 0} ) of the speckle modulator is 10 ° or more when the optical fiber is twisted.

[33] When the length of the refractive index modulator in the light guide direction is Lm, the change in refractive index is Δn / n, and the center wavelength of the spectrum of the illumination pulse is λc, the driving intensity amplitude (I _{mod, 0} ) is the imaging system according to [29], wherein Δn / n ≧ λc / Lm in terms of a change in refractive index of the refractive index modulator.

[34] An endoscope system including the imaging system according to any one of [21] to [33], wherein the imaging system further performs image processing on an image captured by the imager. An endoscope system including a circuit and an image display unit that displays an image subjected to image processing by the image processing circuit.

[35] A microscope system including the imaging system according to any one of [21] to [33], wherein the imaging system further includes an image processing circuit that performs image processing on an image captured by the imager. A microscope system having an image display unit for displaying an image subjected to image processing by the image processing circuit.

[36] An illumination light generator for generating coherent light;
A speckle modulator that modulates speckle generated by the coherent light;
An imager that performs imaging in a predetermined exposure period (t _{pw, exp} );
An imaging system having a synchronization controller that controls the imaging timing of the imager and the driving timing of the speckle modulator in synchronization.

[37] The imaging system according to [36], wherein the synchronous controller controls the speckle modulator to operate at least in the exposure period (t _{pw, exp} ).

[38] The imaging system according to [36] or [37], wherein the speckle modulator periodically changes a driving intensity (I _mod ) of the speckle modulator.

[39] When the exposure period (t _{pw, exp} ) is a period of less than half of the speckle modulation period (t _mod ), the synchronous controller determines that the exposure period (t _{pw, exp} ) [38] The imaging system according to [38], wherein the imager and the speckle modulator are controlled so as to include a time at which a change rate of the driving intensity (I _mod ) of the speckle modulator is substantially maximized.

[40] The synchronous controller may be configured such that the center of the exposure period (t _{pw, exp} ) is a time at which the rate of change of the driving intensity (I _mod ) of the speckle modulator is substantially maximized. And [39] for controlling the speckle modulator.

[41] When the exposure period (t _{pw, exp} ) is a period less than ½ of the speckle modulation period (t _mod ), the synchronous controller determines that the exposure period (t _{pw, exp} ) The imaging system according to [38], wherein the imager and the speckle modulator are controlled so that neither the maximum value nor the minimum value of the driving intensity (I _mod ) of the speckle modulator is included.

[42] In the synchronous controller, the exposure period (t _{pw, exp} ) includes a time at which the drive intensity (I _mod ) of the speckle modulator takes a substantial center value between a maximum value and a minimum value. The imaging system according to [41], which controls the imager and the speckle modulator.

[43] In the synchronous controller, the center of the exposure period (t _{pw, exp} ) is a time at which the driving intensity (I _mod ) of the speckle modulator takes a substantial center value between the maximum value and the minimum value. As described above, the imaging system according to [42], which controls the imager and the speckle modulator.

[44] When the exposure period (t _{pw, exp} ) is a period of ½ or more of the speckle modulation period (t _mod ), the synchronous controller determines that the exposure period (t _{pw, exp} ) [38] The imaging system according to [38], wherein the imager and the speckle modulator are controlled such that the drive intensity (I _mod ) of the speckle modulator includes a time when the maximum value is taken and a time when the speckle modulator takes the minimum value.

[45] The speckle modulator includes a first speckle modulator and a second speckle modulator, and the synchronous controller includes an exposure timing of the imager, the first speckle modulator, and / or the second speckle modulator. The imaging system according to [36], wherein the control is performed in synchronization with the drive timing of the speckle modulator.

[46] When the change width of the drive strength of the speckle modulator that the speckle reduction is saturated with respect to the drive strength change of the speckle modulator is a drive strength threshold width (ΔI _{mod, th} ), The imaging system according to [36] or [37], wherein the driving intensity amplitude (I _{mod, 0} ) of the modulator is set to be equal to or larger than the driving intensity threshold (ΔI _{mod, th} ).

[47] The drive intensity amplitude (I _{mod, 0} ) of the speckle modulator is equal to the drive intensity threshold width (ΔI _mod ) of the drive intensity change width (ΔI _mod ) of the speckle modulator in the exposure period (t _{pw, exp} ). The imaging system according to [46], which is set to have a value equal to or greater than ΔI _{mod, th} ).

[48] The imaging system according to [36], wherein the speckle modulator includes a phase modulator that temporally changes the phase of the coherent light.

[49] The imaging system according to [48], wherein the phase modulator includes a light guide member variation device that mechanically varies a light guide member included in a light guide optical system that guides the coherent light.

[50] The imaging system according to [48], wherein the phase modulator has a concavo-convex plate having a concavo-convex greater than 1/10 of the wavelength of the coherent light.

[51] The imaging system according to [48], wherein the phase modulator is a refractive index modulator that temporally changes a refractive index of a light guide optical system that guides the coherent light.

[52] The imaging system according to [51], wherein the refractive index modulator includes at least one of an electro-optic element and an acousto-optic element.

[53] When the light guide optical system includes an optical fiber, and the core diameter of the optical fiber is Φc, the drive intensity amplitude (I _{mod, 0} ) of the speckle modulator is the vibration of the optical fiber by the light guide member fluctuation device. The imaging system according to [49], wherein the displacement is 5Φc or more.

[54] The imaging system according to [49], wherein the light guide optical system includes an optical fiber, and a driving intensity amplitude (I _{mod, 0} ) of the speckle modulator is 10 ° or more when the optical fiber is twisted.

[55] When the length in the light guide direction of the refractive index modulator is Lm, the change in refractive index is Δn / n, and the center wavelength of the spectrum of the illumination pulse is λc, the driving intensity amplitude (I _{mod, 0} ) is the imaging system according to [51], wherein Δn / n ≧ λc / Lm in terms of a change in refractive index of the refractive index modulator.

[56] An endoscope system including the imaging system according to any one of [36] to [55], wherein the imaging system further performs image processing on an image captured by the imager. An endoscope system including a circuit and an image display unit that displays an image subjected to image processing by the image processing circuit.

[57] A microscope system including the imaging system according to any one of [36] to [55], wherein the imaging system further includes an image processing circuit that performs image processing on an image captured by the imager; A microscope system having an image display unit for displaying an image subjected to image processing by the image processing circuit.

Claims

An illumination pulse generator for generating an illumination pulse of coherent light;
A speckle modulator that modulates speckle generated by the coherent light;
An illumination apparatus comprising: a synchronous controller that controls the pulse generation timing of the illumination pulse generator and the drive timing of the speckle modulator in synchronization.
The illumination device according to claim 1, wherein the synchronous controller controls the speckle modulator to operate at least in a pulse emission period per one illumination pulse.
The lighting device according to claim 2, wherein the speckle modulator periodically changes the driving strength of the speckle modulator.
When the pulse emission period is a period less than half of the speckle modulation period, the synchronous controller determines that the pulse emission period is a time at which the rate of change of the driving intensity of the speckle modulator is substantially maximized. The illumination device according to claim 3, wherein the illumination pulse generator and the speckle modulator are controlled to include
The synchronous controller controls the illumination pulse generator and the speckle modulator so that a center of the pulse emission period is a time at which a change rate of a driving intensity of the speckle modulator is substantially maximized. Item 5. The lighting device according to Item 4.
When the pulse emission period is a period less than half of the speckle modulation period, the synchronous controller includes the pulse emission period that includes neither the maximum value nor the minimum value of the driving intensity of the speckle modulator. The illumination device according to claim 3, wherein the illumination pulse generator and the speckle modulator are controlled.
The synchronous controller includes the illumination pulse generator and the speckle modulator so that the pulse emission period includes a time at which the driving intensity of the speckle modulator takes a substantial center value between a maximum value and a minimum value. The lighting device according to claim 6 to be controlled.
The synchronization controller may be configured such that the center of the pulse emission period is a time at which the driving intensity of the speckle modulator takes a center value between a substantial maximum value and a minimum value. The lighting device according to claim 7, wherein the lighting device controls the modulator.
When the pulse light emission period is a period of ½ or more of the speckle modulation period, the synchronous controller takes the time when the drive intensity of the speckle modulator takes the maximum value and the minimum value. The lighting device according to claim 3, wherein the lighting pulse generator and the speckle modulator are controlled so as to include time.
The speckle modulator includes a first speckle modulator and a second speckle modulator, and the synchronous controller includes a pulse generation timing of the illumination pulse generator, the first speckle modulator, and / or the second speckle modulator. The lighting device according to claim 1, wherein the lighting device is controlled in synchronization with a drive timing of the second speckle modulator.
When the change width of the drive strength of the speckle modulator where the reduction of the speckle is saturated with respect to the drive strength change of the speckle modulator is the drive strength threshold, the drive strength amplitude of the speckle modulator is the drive The lighting device according to claim 2, wherein the lighting device is set to be equal to or greater than an intensity threshold width.
The lighting device according to claim 11, wherein the drive intensity amplitude of the speckle modulator is set such that a change width of the drive intensity of the speckle modulator in the pulse emission period is equal to or greater than a drive intensity threshold.
The lighting device according to claim 1 or 2, wherein the speckle modulator includes a phase modulator that temporally changes the phase of the coherent light.
14. The illumination device according to claim 13, wherein the phase modulator has a light guide member changing device that mechanically changes a light guide member included in a light guide optical system that guides the coherent light.
The illuminating device according to claim 13, wherein the phase modulator has a concavo-convex plate having a concavo-convex greater than 1/10 of the wavelength of the coherent light.
The lighting device according to claim 13, wherein the phase modulator is a refractive index modulator that temporally changes a refractive index of a light guide optical system that guides the coherent light.
The illumination device according to claim 16, wherein the refractive index modulator includes at least one of an electro-optic element and an acousto-optic element.
The light guide optical system includes an optical fiber, and assuming that the core diameter of the optical fiber is Φc, the drive intensity amplitude of the speckle modulator is 5Φc or more in terms of the displacement of the vibration of the optical fiber by the light guide member variation device. Item 15. The lighting device according to Item 14.
The illuminating device according to claim 14, wherein the light guide optical system includes an optical fiber, and the driving intensity amplitude of the speckle modulator is 10 ° or more when the optical fiber is twisted.
When the length of the refractive index modulator in the light guide direction is Lm, the change in refractive index is Δn / n, and the center wavelength of the spectrum of the illumination pulse is λc, the drive intensity amplitude of the speckle modulator is the refractive index modulator. The illumination device according to claim 16, wherein Δn / n ≧ λc / Lm with respect to a change in refractive index.
An imaging system comprising: the illumination device according to any one of claims 2 to 12; and an imager that performs imaging in a predetermined exposure period.
The imaging system according to claim 21, wherein the synchronization controller controls the pulse generation timing of the illumination pulse generator, the driving timing of the speckle modulator, and the imaging timing of the imager in synchronization.
The synchronization controller controls the pulse generation timing of the illumination pulse generator, the driving timing of the speckle modulator, and the imaging timing of the imager in synchronization, and the illumination pulse generator is configured to control the illumination during the exposure period of the imager. The imaging system according to claim 21, wherein the imaging system is controlled to generate a pulse.
The synchronous controller controls the pulse generation timing of the illumination pulse generator, the drive timing of the speckle modulator, and the imaging timing of the imager in synchronization,
The drive intensity amplitude of the speckle modulator is defined as I mod, 0 ,
The change width of the drive intensity of the speckle modulator that the reduction of the speckle is saturated with respect to the change of the drive intensity of the speckle modulator is expressed as ΔI mod, th ,
T pw, ill , the pulse emission period of the illumination pulse generated by the illumination pulse generator,
The modulation period when the speckle modulator is periodically driven is t mod ,
When M 0 = I mod, 0 / ΔI mod, th ,
The imaging system according to claim 21, wherein the synchronous controller drives the speckle modulator and the illumination pulse generator with M 0 ≧ 1, and further drives with t mod ≦ 2M 0 t pw, ill .
The synchronous controller controls the pulse generation timing of the illumination pulse generator, the drive timing of the speckle modulator, and the imaging timing of the imager in synchronization,
The drive intensity amplitude of the speckle modulator is defined as I mod, 0 ,
The speckle modulator of the speckle modulator [Delta] I mod the drive strength threshold width variation width of the drive strength reduction of speckle is saturated with respect to a change in drive strength, th,
The pulse emission period of the illumination pulse generated by the illumination pulse generator is expressed as t pw, ill ,
The modulation period when the speckle modulator is periodically driven is t mod ,
When M 0 = I mod, 0 / ΔI mod, th ,
The imaging according to claim 21, wherein the synchronous controller drives the speckle modulator and the illumination pulse generator with M 0 ≧ 1, and further drives with t pw, ill <t mod ≦ M 0 t pw, ill. system.
An endoscope system including the imaging system according to any one of claims 21 to 25, wherein the imaging system further includes an image processing circuit that performs image processing on an image captured by the imager; An endoscope system having an image display unit that displays an image subjected to image processing by the image processing circuit.
A microscope system including the imaging system according to any one of claims 21 to 25, wherein the imaging system further includes an image processing circuit that performs image processing on an image captured by the imager, and the image A microscope system having an image display unit that displays an image subjected to image processing by a processing circuit.
An illumination light generator for generating coherent light;
A speckle modulator that modulates speckle generated by the coherent light;
Having an imager for imaging in a predetermined exposure period;
An imaging system having a synchronization controller that controls the imaging timing of the imager and the driving timing of the speckle modulator in synchronization.
29. The imaging system according to claim 28, wherein the synchronous controller controls the speckle modulator to operate at least during the exposure period.
30. The imaging system according to claim 28 or 29, wherein the speckle modulator periodically changes the driving intensity of the speckle modulator.